refactor(ngSwitch):delete default directive restriction

[diegofss11]

Delete the directive restriction to avoid code duplication since the default is already applied

This line is uneccesary because the default value is set inside the registerDirective function:

directive.index = index;
directive.name = directive.name || name;
directive.require = directive.require || (directive.controller && directive.name);
directive.restrict = directive.restrict || 'EA';

PR baked during http://www.meetup.com/AngularJS-BH/events/220033641/